1. Field of the Invention
This invention relates generally to the art of comminuting hard materials, and more particularly to ball tube mills.
The invention can find application in the cement industry, in mining, and for other industrial uses, where fine grinding of materials is essential.
2. Description of the Prior Art
There is known a ball tube mill comprising a rotatable housing with a lined inside surface and end bottom plates having inlet and outlet holes. Arranged inside the housing at an angle to its longitudinal axis is a perforated wall dividing the interior of the housing into coarse and fine grinding chambers. The inside surface of the lining of the housing in the two grinding chambers is cylindrical in shape (cf., SU, A, 733,727).
In the above ball tube mill having a cylindrical lining of the inside surface of the housing the grinding bodies are forced to move from the perforated wall by the plane of this wall.
In the reverse direction (viz., to under the perforated wall), the grinding bodies move spontaneously less vigorously. As a result, the grinding bodies fail to uniformly occupy the entire volume of the grinding chambers of the mill. This is caused essentially because the surface formed by the grinding bodies present in each grinding chamber of the mill substantially extends in the direction of the longitudinal axis of the housing at an angle equal to the slope of the grinding bodies.
The inclination of the surface of the grinding bodies (angle of slope) corresponds to the direction of inclination of the perforated wall and changes during the cycle to the opposite direction.
Non-uniform utilization of the working volume of each grinding chamber generally results in reduced efficiency of the grinding process.